This article identifies and explains the effects of one of the philosophical assumptions underlying takings, perhaps the one that is most fundamental: one's view of the nature of the police power. This article also explains and documents the early or original assumptions about aspects of police power that are at the center of takings controversies, including the purposes for which the police power may be exercised in regulating private property, and the circumstances under which a landowner impacted by police power regulations may be entitled to compensation.

This article adds two new pieces to the historical puzzle of if and when to compensate for regulatory takings. These pieces are a more detailed description of the common law concepts of the police power and an analysis of early state cases on compensation practices for physical and regulatory takings.

Section II of this article explains the origins and character of police power in Anglo-American law. Section III reveals the widespread early assumptions about limitations on the purposes for which the police power could be used. Section IV details to what extent compensation was required for police power regulation of land in the early American cases. Section V shows how the historical background of police power suggests a compelling rationale for the rules by which contemporary police power regulations may be imposed and compensated.

Based on these analyses, Section VI argues that exercises of police power are not presumptively exempt from compensation requirements; that exercises of police power for affirmative purposes beyond suppression of nuisances should be subject to compensation requirements; and that compensating for police power regulations affecting property rights to achieve affirmative social benefits complies with both the letter and spirit of the constitutional compensation requirement.